algae and protozoa - exam 2

algae

• eukaryotic organisms

• photosynthetic

  • contain chloroplasts

  • contain chlorophyll

    • also have other pigments that contribute to algaes color

chloroplasts

organelles needed for photosynthesis

chlorophyll

primary pigment

• green pigment for photosynthesis

characteristics of algae

• unicellular or colonial or filamentous forms

  • larger forms have tissues and simple organs

• inhabit fresh and marine waters

• major component of plankton

  • large floating community of microscopic organisms

• asexual and sexual reproduction

asexual reproduction of algae

can be via binary fission, fragmentation or spores

sexual reproduction of algae

union of male and female gametes

types of algae

• euglenids

• dinoflagellates

• diatoms

• brown algae/ kelps

• red seaweeds

• green algae

diatoms

• single-cells algae with silica in cell walls and golden pigment in chloroplast

• diatomaceous earth

• major component of plankton

brown algae/ kelps

phaeophyta

red seaweeds

rhodophyta

• source of agar and carrageenan

agar

solidifying agent of media

green algae

chlorophyta

• precursor of higher plants

benefits of algae

• major role in aquatic food webs and contribute to oxygen in atmosphere

• potential for use of biofuels

animal/ human tissues are not typically hospitable to algae

so there are not many algal pathogens

• there is an exception

prototheca

unusual non-photosynthetic algae associated with skin and subcutaneous infections in animals and humans (rare in humans)

primary health threat of algae is associated with

algal toxins

• dinoflagellates can overgrow and result in a harmful algal bloom (HAB)

• other aquatic organisms accumulate the toxin

• we ingest these and get ill from the toxins

paralytic shellfish poisoning is caused by

eating toxin-containing clams and other invertebrates

paralytic shellfish poisoning symptoms

severe neurological symptoms; can be fatal

paralytic shellfish poisoning treatment

no treatment other than life-support systems like respirators until toxin passes from the system

ciguatera is caused by

eating toxin-containing fish like bass and mackerel

• cooking cannot destroy toxin

• no antidote

ciguatera symptoms

nausea, vomiting, diarrhea, stomach pain

ciguatera treatment

no specific treatments; IV medications can be attempted

Pfiesteria piscicida

• normally non-toxic but can shift to toxic forms

• toxin causes severe infections and lesions in fish

• humans can get infected when exposed to infected fish or contaminated water

Pfiesteria piscicida symptoms

skin lesions, headache, abdominal issues, eye irritation

Pfiesteria piscicida treatment

most cases are resolved without treatment

specific algal intoxications

• paralytic shellfish poisoning

• ciguatera

• Pfiesteria piscicida

protozoa

• eukaryotic organisms

• single celled (with major eukaryotic organelles except for chloroplasts)

• most are heterotrophic

heterotrophic protozoa

• some have oral grooves which direct food into vacuoles for digestion

• some absorb directly through cell membrane

• some are parasites and feed on host

characteristics of protozoa

• 2 types of cytoplasm

• lack a cell wall

• cell shape can be static or changing

main limiting factor in environment of protozoa

availability of moisture

predominant habitats for protozoa

fresh water, marine water, soil, plants and animals

protozoa locomotion

apicomplexa

nonmotile

protozoa locomotion

modes of motility

• pseudopods

  • projections of cytoplasm (false feet)

• flagella

• cilia

life cycles of protozoans

• trophozoite

• cyst

trophozoite cycle

motile feeding stage; needs plenty of food and moisture

cyst cycle

dormant, resting stage when conditions become unfavorable; can survive adverse periods and are an important factor is spread of disease

• when cyst is provided with moisture and nutrients it will break open and release an active trophozoite

reproduction of protozoa

• life cycles vary from simple to complex

• asexually and sexually

asexual reproduction of protozoa

• usually mitosis

• some parasitic species reproduce by multiple fission (schizogony)

sexual reproduction of protozoa

conjugation

taxonomy of protozoa

• supergroup SAR

• supergroup Excavata

• supergroup Ameobozoans

supergroup SAR

includes apicomplexans and ciliates

supergroup Excavata

includes flagellated protozoans

supergroup Amoebozoans

includes amoeboid protozoans

supergroup SAR- apicomplexans

have apical complex to penetrate host cells; nearly all are parasitic and have complex life cycles

• lack locomotion in the trophozoite state

ex. Plasmodium (causes malaria), Toxoplasma (causes toxoplasmosis)

which apicomplexan causes malaria

plasmodium

which apicomplexan spreads to humans via vector (anopheles mosquito bite)

plasmodium

which apicomplexan has a complicated life cycle involving red blood cells and liver cells

plasmodium

plasmodium symptoms

• malaise

• aches

• nausea

• chills

• fever

• sweating

cyclical, lining up with rupturing of red blood cells

which apicomplexan causes toxoplasmosis

toxoplasma gondii

which apicomplexans primary reservoir are felines and their rodent prey

toxoplasma gondii

which apicomplexan has mainly asymptomatic cases

toxoplasma gondii

toxoplasma gondii in pregnant women

have 1/3 chance of passing it to fetus; may result in still birth and severe abnormalities of fetal organs

supergroup SAR- ciliates

• have cilia for motility

• have 2 types of nuclei

• most are free living

ciliates, 2 types of nuclei

• macronucleus

• micronucleus

macronucleus of ciliates

has genes that control feeding and waste removal

micronucleus of ciliates

exchanged during conjugation for genetic variability

only one ciliated human parasite

Balantidium coli

• acquired by ingesting cyst-containing food or water

• trophozoites cause intestinal symptoms

Balantidium coli causes

balantidiasis

• bloody and mucus-filled diarrhea

Balantidium coli treatment

tetracycline, metronidazole

supergroup excavata examples

• Giardia intestinalis

• Trichomonas vaginalis

• Trypanosoma cruzi

• Trypanosoma brucei

Trypanosoma brucei

causes sleeping sickness

• vector is tse-tse fly

Trypanosoma cruzi

causes chagas disease

• vector is reduviid bug

Trichomonas vaginalis

causes trichomoniasis

• must be passed from person to person because it has no cyst form

Giardia intestinalis

causes giardiasis

supergroup amoebozoans examples

• Naegleria fowleri

• Entamoeba histolytica

Naegleria fowleri

causes primarily amebic meningoencephalitis

• lives naturally in water (fresh water)

• cases usually occur in children

Entamoeba histolytica

• always association with humans

• cyst is very important for disease transmission

Entamoeba histolytica route of infection

ingestion of food and water contaminated with human feces

Entamoeba histolytica common symptoms

GI disturbances leading to weight loss and dehydration

Entamoeba histolytica preventative measures

sewage treatment, prevention of the use of human feces as fertilizer, adequate sanitation of food and water